Edwabd weston



(No Model.)

B. WESTON. ELBGTROPLATED COIL FOR ELECTRICAL MEASURING INSTRUMENTS. No.392,885. Patented Nov. 6, 1888.

g IIVVEIVTOR- I B) SATTOR/VEY,

Nv PETERS Phowumu hcr, Washingficn, 11.0v

UNITED STATES ParaN'r EDWARD WESTON, OF NEVARK, NEW JERSEY, ASSIGXOR TOTHE XVESTON ELECTRICAL INSTRUMENT OOliIPANY, OF SAME PLACE.

ELECTROPLATED COIL FOR ELECTRICAL MEASURING-INSTRUMENTS.

SPECIFICATION forming part of Letters Patent No. 392,385, dated November6, 1888.

Application filed April 9, 1888. Serial No. 270,093. (No model.)

To ctZZ whom it may concern.-

Be it known that I, EDWARD iX nsrorv, of Newark, Essex county, NewJersey, have in vented a new and useful Improvement in ElectroplatedCoils for Electrical Measuring-Instruments, of which the following is aspecification.

My invention relates to a coil which in certain electricalmeasuring-instruments is sup- 1o ported so as to move freely in amagnetic field, and through which a current to be measured is passed.The passage of the current causes a movement of said coil against auniform rcsilient resistance, and the strength of the cur- 1- rent isindicated by the extent of movement of said coil.

In another application for Letters Patent, filed on the 17th day ofMarch, 1888, and se rially numbered 267,47i,l have fully described anapparatus wherein such a coil is used in the manner described.

My present invention has more particular reference to the constructionof said coil and to the covering or envelope thereof, which is 2 ofdiamagnetic metal. It is a well-known fact that when a body ofdiamagneticmetalsuch as copperis suspended between the poles of apowerful magnet it finds in the field of force a powerful resistingmedium which opposes 0 any motion of the metallic mass and speedilybrings it to rest. To this end I inclose my coil in a mass of copper,and so render theneedle or pointer attached to the coil and indicatingthe extent of its motion deadbeat or free from undue oscillation orvibration. While this envelope of copper may be applied to the coil inthe form of plates soldered or otherwise secured together, I find itvery much more advantageous and convenient 0 to deposit the copper onthe coil by electroplating,because in this way I can produce a perfectenvelope withontjoints of homogeneous metal, which by simplemanipulation of the electrode in the plating-bath I can deposit in 5 athick mass atone point or a thin mass atan' other, as may be desired.

In the accompanying drawings, Figure l is a face view of my coil havingacovering of electro-deposited metal, part of said coil and envelopebeing shown'in section on the line :t

at of Fig. 2. Figs. 2 andS are sections of my coil on the lines 3/ y andof Fig. 1, respect ively. Fig. 4 is a vertical transverse section of acoil having only an outer peripherical covering of eleetro-depositedmetal. Fig. 5 is 5 5 a similar section of a coil having only an innercovering or coil of electro-deposited metal. Fig. 6 isa perspective viewof a coil having only side or face pieces of electro-deposited metal.

Similar letters of reference indicate like parts.

A is the coil of insulated wire, which may be of any desired form. It ishere shown as quadrangular. The exterior of this coil is 6 5 coveredwith electro-deposited copper to form an envelope or covering, which maybe regarded as consisting of an inside frame, 13, an outer frame, 0, andside or face pieces, D D. This envelope is in one piece, as here shown,and for the purposes of the electrical measuring-instrument referred toin my above-notcd application it comprises the parts before named; butit is to be understood that I do not limit my present invention to anelectro- 7 deposited envelope covering the entire exterior of the coil,because I may for some purposes use only an inner frame, B, or an outerframe, 0, or only the side pieces, D D, in each case, however, producingthe part of electro- So deposition. Thus in Fig. at is shown a coilhaving only an outer frame, C. Fig. 5 repre sents a coil having only aninner frame, B, or core. Fig. 6 represents a coil having only face orside pieces, D. So, also, I make the 8 coil with any two of these parts,as the frame 0 and side pieces, D, or frame 0 and frame or core B, orframe or core 13 and side pieces, D.

I may produce this electro-deposited covering by various methods, one ofwhich I will now 0 specify, by following which any one skilled in theart will easily be able practically to make my invention.

I wind the coil upon any suitable form and permeate it with shellac orany other suitable adhesive material, whereby all the turns of wire arefirmly fastened together. When the shellac is dry, I remove the coilfrom the form and dip it in melted beeswax, so that a film of wax isleft adherent. Upon the wax I ap- 10o ply a coating of plumbago and thenplace the coil in any suitable electrodeposition, both arranged forcopper deposit. In order to effect the deposition of the inside frame,one anode may be supported inside the coil, and generally the anodes areto be arranged so as to effect the deposition at the points needed tosecure deposits of the desired continuity and thickness. Any one skilledin the manipulation of electroplating-baths will have no difficulty inmaking such arrangement.

For practical use I make the outer frame, 0, thicker than the innerframe, B, so as to secure the greater mass of diamagnetic metal on theoutside of the coil, and hence in the densest part of the magnetic fieldof force surrounding the coil, by which means I obtain a more efficientretarding effect of the copper when the coil moves in the field.

It will be obvious that by producing the copper core, side pieces, orouter frame, or all of them, in this way, I obtain all parts of strictlyhomogeneous diamagnetie mctal,-and so secure uniformity of actionthereof in the magnetic field. In delicate instruments of precision thisis an important desideratum. So, also, I avoidpossibility of portionsbeingundulythiek or thin or more or less dense than others, and thenecessity of any soldering or brazing or of cutting the parts to make aproper fit. The

terminals E of the coil are carried out through the outer frame, asshown.

I claim 1. An insulated conductor in coil form having an inner frame orcore of clectro-deposited metal, substantially as described.

2. An insulated conductor in coil form having an outer periphericalcovering or frame of electro-deposited metal, substantially as described.

3. An insulated conductor in coil form having a face or side covering ofelectro-depositcd metal, substantially as described.

i. An insulated conductor in coil form wholly covered on its exteriorwith electro' deposited metal, substantially as described.

5. An insulated conductor in coil form having a covering ofelectro-deposited diamagnetie metal, substantially as described.

(3. An insulated conductor in coil form wholly covered on its exteriorwith electrodeposited diamagnetic metal, the deposit on the periphery ofthe coil being thicker than elsewhere, substantially as described.

EDWARD WESTON.

Witnesses:

BARK BENJAMIN, EDGAR GooDwrN.

